Double active drive mechanism

ABSTRACT

A double acting drive mechanism (10) includes a driving member (12) and a pair of driven members (16) and (18) which carry a small diameter pulley face (24) and a larger diameter pulley face (26) respectively. A clutch mechanism (34) normally couples one of the driven members (16) for rotation with the driving member (12) and the driven member (18) freewheels. Upon energization of the electromagnetic actuator (48), the armature (56), which rotates with the other driven member (18), engages the clutch mechanism (34) to couple the other driven member (18) for rotation with the driving member (12). Engagement of the armature (56) with the clutch mechanism (34) disengages the clutch mechanism (34) from the one driven member (16).

This invention relates to a double acting drive mechanism.

Modern automotive vehicles are normally provided with a number ofbelt-driven engine accessories, such as a power steering pump, analternator, and an air conditioning compressor. Since these accessoriesmust be designed to provide sufficient output at relatively low enginespeeds, driving these accessories at higher than their design speedswastes power and, accordingly, increases fuel consumption. However, suchaccessories have normally been driven by a direct belt drive from theengine at a speed that is a predetermined function of the engine speed.Furthermore, these accessory devices exert a parasitic drag on thevehicle engine during vehicle accelerations. Although this effect washardly noticeable when most vehicle engines were relatively large, thisparasitic drag of the belt-driven accessories is a significant factorwhich detracts from the performance of the smaller four cylinder enginesnow in common use.

Accordingly, the present invention saves fuel and increases engineperformance by permitting the vehicle engine driven accessories to bedriven through either of two belt drives, one of which provides a higherspeed and the other of which provides a lower speed. Appropriate sensorsare used to sense engine operating conditions such that the slower speedis desirable, and the double acting drive mechanism of the presentinvention is switched from the higher speed drive to the lower speeddrive by the sensors.

While the invention has been disclosed with respect to a vehicle engineaccessory drive, it may be used whether a selectively actuatable,two-belt drive is necessary, either on an automotive vehicle orelsewhere, such as on industrial machines. The scope of the invention isto be limited only by the scope of the appended claims.

Other features and advantages of the invention will be apparent in thefollowing description with reference to the accompanying drawing inwhich the sole FIGURE is a longitudinal cross-sectional view of a doubleacting drive mechanism made pursuant to the teachings of my presentinvention.

Referring now to the drawings, the present invention permits driving ofthe vehicle engine accessories by either one of two separate belts sothat the pulley ratios of these two separate belts are different.Accordingly, a two-speed drive is provided. With respect to the drawing,the double acting drive mechanism generally indicated by the numeral 10includes a driving member 12 that is driven by the vehicle enginethrough the splined connection 14. A pair of driven members 16, 18 aremounted for rotation with respect to the driving member 12 throughbearings 20, 22, respectively. The driven member 16 includes a smalldiameter pulley face 24 and the driven member 18 includes a largerdiameter pulley face 26. The driven member 16 includes a radiallyprojecting portion 28 mounted for rotation with the pulley face 24 thatterminates in an axially extending portion 30 which presents acircumferentially extending engagement surface 32. The double actingdrive mechanism 10 further includes a clutch member generally indicatedby the numeral 34 which includes a circumferentially extending, radiallyprojecting adapter 36 which carries axially extending tangs 38. Tangs 38are slidably received in apertures 40 in a pressure plate 42 carried bythe tangs 38. A circumferentially extending band of friction material 44is carried on the pressure plate 42. A spring 46 yieldably urges thepressure plate 42 with the friction material 44 into engagement with theengagement surface 32.

Selectively actuatable means, such as an electromagnetic actuatorgenerally indicated by the numeral 48, includes an electromagnetic coil50 wrapped circumferentially around the driving member 12 and supportedwithin housing 52. The housing 52 is supported on the driving member 12through a bearing 54 and is held non-rotatable by a bracket (not shown)securing the housing 52 to a non-rotative part of the vehicle. Actuator48 includes an armature 56 which is slidably mounted on a tang 58projecting from a bracket 60 which is a part of the driven member 18.Accordingly, the armature 56 is mounted for rotation with the drivenmember 18 and for axial sliding movement relative thereto. As is wellknown to those skilled in the art, energization of the coil 50 causesthe armature 56 to move toward the coil. The radial outermost portion 62of the armature 56 presents a circumferentially extending engagementface 64 that is adapted to engage the portion 66 of the frictionmaterial 44 adjacent thereto.

In operation, rotation of the driving member 12 also rotates the adapter36. Rotation of the adapter 36 is transmitted to the radially projectingportion 28 of the driven member 16 through the pressure plate 42, thefriction material 44 and the engagement surface 32. Accordingly, thesmaller diameter pulley face 24 is normally driven by the driving member12 and the larger diameter pulley face 26 free wheels on the bearing 22,due to the fact that the armature 56 is separated from the drivingconnection with the pressure plate 42.

When the aforementioned vehicle speed and/or acceleration sensors sensea vehicle operating condition in which it is desirable to drive theaforementioned accessories through the larger diameter pulley 26 insteadof the smaller diameter pulley 24, the coil 50 is energized, therebymoving the armature 56 toward the coil 50. Movement of the armature 56engages the engagement face 64 with the portion 66 of the frictionmaterial 44 attached to pressure plate 42. Additional movement of thearmature 56 forces the friction material 44 away from the engagementsurface 32, thereby breaking the driving engagement between the drivingmember 12 and the driven member 16 and initiating driving engagementbetween the driving member 12 and the driven member 18 through thedriving engagement between the engagement face 64 and the portion 66 ofthe friction material 44. Accordingly, the smaller diameter pulley 24 isthen allowed to free-wheel on the bearing 20, and the driving engagementis established between the driving member 12 and the larger diameterpulley face 26 through the driven member 18. When the coil 50 is laterdeenergized, the spring 46 forces the pressure plate 42 to bring thefriction material 44 back into driving engagement with the engagementsurface 32, thereby reestablishing the driving connection between thedriving member 12 and the driven member 16.

I claim:
 1. Double acting drive mechanism comprising:a rotatable drivingmember, a pair of rotatable driven members coaxial with said drivingmember, and clutch means selectively shiftable from a first conditionfor coupling one of said driven members to said driving member to asecond condition, coupling the other driven member to the drivingmember, said clutch means including first axially movable means mountedfor rotation with said driving member, resilient means yieldably urgingthe first axially movable means into frictional engagement with said onedriven member, second axially movable means mounted for rotation withthe other member, and selectively actuatable means for moving saidsecond axially movable means into engagement with the first axiallymovable means wherein, said one driven members includes an engagementface, said first axially movable means including a support mounted forrotation with said driving member, a pressure plate slidably mounted onsaid support and carrying an engagement surface, said resilient meansbeing carried by said support and acting against said pressure plate tourge the engagement surface into driving engagement with said engagementface.
 2. Double acting drive mechanism as claimed in claim 1 whereinsaid selectively actuatable means moves said second axially movablemeans into engagement with said pressure plate upon actuation of theselectively actuatable means and moves said engagement surface out ofdriving engagement with said engagement face.
 3. Double acting drivemechanism as claimed in claim 2 wherein said engagement surface includesa portion drivingly engaged by said second axially movable means toprovide a driving connection between said support and said secondaxially movable means through said pressure plate after said secondaxially movable means moves said pressure plate to break the drivingengagement between the engagement surface and the engagement face. 4.Double acting drive mechanism as claimed in claims 1, 2 or 3, whereinsaid selectively actuatable means includes an electromagnetic actuatorhaving an armature, said armature being defined by said second axiallymovable means.
 5. A two speed drive (10) for an internal combustionengine comprising:a driving member (12) adapted to be driven by theengine; two driven members (16, 18) mounted on respective bearings (20,24) to said driving member (12); the first of said driven members (16)supporting a first pulley face (24) and the second of said drivenmembers (18) supporting a second pulley face (26) of larger diameterthan said first pulley face and rotatable with said driving member (12),said first driven member (16) comprising a radially projecting portion(28) mounted for rotation with said first pulley face (20) and anaxially extending portion (30) which terminates at a circumferentiallyextending engagement surface (32); a clutch member (34) includes acircumferentially extending, radially projecting adapter (36) positionedbetween said first and said second driven members (16, 18) and aplurality of axially projecting tangs (38) extending towards andreceived within a depression within said second driven member (18); anannular pressure plate (42) having apertures (40) into which each ofsaid tangs (38) extend, said pressure plate (42) being rotationallysupported by said tangs (38), said pressure plate including a firstcircumferentially extending band (44) of friction material mounted forengagement with said engagement surface (32), said pressure plate (42)further supporting a second circumferentially extending band (66) offriction material positioned interior to said first band (44); springmeans (46) mounted within said depression of said second driven member,attached to each of said tangs (38) for biasing said pressure plate (42)into engagement with said engagement surface (32) of said first drivenmember (16); an electromagnetic actuator (48) adapted to be secured to anonrotating element of the engine, including a nonrotating coil (50)supported on bearings relative to said driving member, and positioned onone side of said second driven member (18) away from said first drivenmember (16), said actuator including an armature plate (56) positionedbetween said second driven member (18) and said adapter (36), saidarmature plate (56) rotationally fixed to said driving member, saidplate further axially movable relative to said second driven member inresponse to magnetic flux generated by said coil, said plate engagablypositioned relative to said second band of friction material so as tomove said pressure plate (42) from engagement with said engagementsurface of said first driven member thereby decoupling said first drivenmember from said driving member in response to energization of saidelectromagnetic actuator.